This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-085424, filed Mar. 24, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a head suspension assembly (hereinafter abbreviated as a HSA) and particularly to a HSA mounting a head IC together with a magnetic head, and a magnetic disk apparatus comprising the HSA.
In general, a magnetic disk apparatus comprises a magnetic disk, a spindle motor for supporting, rotating the magnetic disk, a carriage assembly for supporting and driving a magnetic head, a voice coil motor for driving the carriage assembly, and a main flexible printed circuit board (hereinafter called as a main FPC) for electrically connecting the magnetic head to a control section, which are arranged in a case.
The carriage assembly includes a bearing unit attached to the case, and a plurality of HSAs extending from the bearing unit. The magnetic head is mounted on the extended end portion of each HSA. This HSA has an arm made of a thin metal plate spring and having a proximal end portion which is supported on the bearing unit, an elongate suspension extending from the distal end of the arm and supporting the magnetic head on its distal end portion, and an elongate trace adhered on the suspension and arm. The magnetic head is connected to the main FPC through the trace. This trace is constructed by layering a relay flexible printed circuit board on a thin metal lined plate, for example, made of stainless or the like.
The main FPC has a connection end portion fixed on the bearing unit by a screw, and a proximal end portion connected to the control circuit board fixed to the case. Also, the main FPC has a plurality of connection pads provided at the connection end portion, and a plurality of wiring patterns extending from these connection pads to the proximal end portion. Further, the proximal end portion of the trace extending from the magnetic heads is soldered on the connection pads provided at the connection end portion of the main FPC. In this manner, the magnetic heads are electrically connected to the control circuit board and controlled by this control circuit board.
Meanwhile, the head IC (signal processing IC, integrated circuit element) which amplifies a signal read from the magnetic recording medium by the magnetic head is generally equipped on the control circuit board. In contrast, recently, the length of each wiring pattern from the magnetic head to the head IC can be shortened so that the inductances and capacitances of the wiring patterns can be reduced by mounting the head IC on the trace of the HSA near the magnetic head, as shown in Japanese Patent Application KOKAI Publication No. 11-213365, for example. In addition, a proposal has been made for a HSA equipped with a capacitor (capacitor element) for smoothening the power source.
If the head IC is thus equipped on the HSA, total five wiring patterns, i.e., two signal lines, two power lines (Vcc and Vee), and one ground line (GND) are formed on the trace.
Meanwhile, in the main FPC connected with the trace, independent five wiring patterns are provided in correspondence with one trace. Therefore, for example, the main FPC in a magnetic disk apparatus comprising four HSAs has twenty independent wiring patterns and two wiring patterns for VCM, so that the entire width of the main FPC becomes large. Further, this main FPC constructs a movable part which shifts in accordance with rotation of the head actuator. Therefore, if the width is increased, the main FPC undesirably causes a resistance when the head actuator moves.
Also, the FPC forming part of the trace has a structure in which wiring patterns made of copper foil are sandwiched between insulation layers made of polyimide or the like. Further, the wiring patterns of the FPC which is electrically connected with the head IC are covered with insulation layers, a lining plate having a low heat conductivity, and a suspension, so that only poor heat radiation is attained. Therefore, it is difficult to radiate efficiently heat generated from the head IC, and the temperature of the head IC may exceed a guaranteed temperature range. Further, heat from the head IC transfers to the magnetic head so that the characteristics of the magnetic head change, and the lining plate of the trace and the suspension may thermally expand thereby changing the characteristics of the entire HSA.
In addition, if circuits in the head IC that generate heat of high calorie are not provided symmetrically in the right and left sides with respect to the center line of the HSA, thermal expansion is not symmetrical between the left and right sides in the part which supports the magnetic head of the suspension. Consequently, the characteristics of the magnetic head may be deteriorated.
If the head IC and the capacitor are installed on the HSA, the capacitor cannot be thinned more than the head IC because of its structure, and therefore, the capacitor may contact the magnetic disk surface when the magnetic disk apparatus receives an impact or the like and is deformed thereby.
The present invention has been made in view of the above circumstances, and has an object of providing a head suspension assembly capable of reducing influences from heat of the head IC and maintaining excellent characteristics and a magnetic disk apparatus comprising the head suspension assembly.
The present invention has another object of providing a head suspension assembly on which a capacitor can be installed without damaging the magnetic disk and a magnetic disk apparatus comprising the same.
The present invention further has another object of providing a magnetic disk apparatus capable of reducing the number of wiring lines of the main FPC and of reducing thereby the entire width.
To achieve the above objects, a head suspension assembly according to the present invention comprises: a suspension having a distal end portion on which a magnetic head is mounted; a flexible printed circuit board arranged on the suspension with a lining plate interposed therebetween; and a head IC mounted on the flexible printed circuit board and positioned near the magnetic head. The flexible printed circuit board includes a first wiring pattern which electrically connects the magnetic head with the head IC, a second wiring pattern which extends from the head IC to a proximal end portion of the suspension, and insulation films which cover the first and second wiring patterns from both sides, and the insulation films are removed from an area which faces the head IC, and the lining plate and the suspension has an opening in the area which faces the head IC such that the first and second wiring patterns are exposed through the opening.
Also, according to another head suspension assembly of the present invention, the flexible printed circuit board includes a first wiring pattern which electrically connects the magnetic head with the head IC, a second wiring pattern which extends from the head IC to a base end side of the suspension, and insulation films which cover the wiring patterns from both sides. The insulation films are removed from an area which faces the head IC, and the lining plate and the suspension has an opening at the area which faces the head IC. A heat radiation member is provided in the opening, kept in contact with the wiring patterns.
Further, another head suspension assembly according to the present invention comprises: a suspension having a distal end portion on which a magnetic head is mounted; a flexible printed circuit board installed on the suspension with a lining plate interposed therebetween; a head IC mounted on the flexible printed circuit board and positioned near the magnetic head; and a heat radiation member covering an outer surface of the head IC.
According to the head actuator assemblies having the above mentioned construction, the heat radiation efficiency of the head IC is improved so that temperature increase exceeding a guaranteed temperature range of the head IC, characteristic changes of the magnetic head, and deterioration of mechanical characteristics of the suspension due to heat can be prevented.
Also, according to another head actuator assembly of the present invention, the suspension and the lining plate are welded to each other at a welding point positioned between the slider and the head IC. Further, the trace is formed at the lining plate and has an opening positioned between the welding point and the head IC.
In the structure as described above, heat from the head IC can be transmitted to the suspension through the welding point, and heat is hindered from transferring to the magnetic head by providing an opening. In this manner, temperature increase exceeding the guaranteed temperature range of the head IC, characteristic changes of the magnetic head, and deterioration of mechanical characteristics of the suspension due to head can be prevented.
Further, according to another head suspension assembly of the present invention, the head IC has a write driver circuit and a bias current circuit which are each arranged symmetrically with respect to a center axis of the suspension.
In the structure as described above, stable operation can be assured steadily without breaking the balance of the suspension even if the suspension is thermally expanded due to head from the head IC.
Another head suspension assembly according to the present invention comprises: a suspension having a distal end portion on which a magnetic head is mounting; a flexible printed circuit board installed on the suspension with a lining plate interposed therebetween; a head IC mounted on the flexible printed circuit board and positioned near the magnetic head; and a capacitor mounted on the flexible printed circuit board between the magnetic head and the head IC and arranged closer to the distal end side of the suspension than the head IC.
With the structure as described above, the capacitor which has a greater height than the head IC is provided closer to the magnetic head than the head IC, i.e., closer to the distal end side of the suspension. As a result, height margins increase with respect to the magnetic disks, so that damages on the head suspension assembly and the magnetic disks can be reduced.
Meanwhile, a magnetic disk apparatus according to the present invention is constructed by comprising any one of the head suspension assemblies described above.
Another magnetic disk apparatus according to the present invention comprises: a magnetic disk; a plurality of magnetic heads for recoding/reproducing of information with respect to the magnetic disk; a carriage assembly supporting the magnetic heads movably with respect to the magnetic disk, the carriage assembly including a bearing unit, and a plurality of head suspension assemblies each which has a proximal end portion supported by the bearing unit and a distal end portion on which one of the magnetic heads is mounted; and a main flexible printed circuit board having a connection end portion attached to the carriage assembly, and a proximal end portion positioned apart from the connection end portion.
Each of the head suspension assemblies includes an arm extending from the bearing unit, a suspension projecting from an extended end of the arm, an elongate relay flexible printed circuit board provided on the arm and the suspension and having a distal end portion connected to the magnetic head and a proximal end portion connected to the connection end portion of the main flexible printed circuit board, and a head IC mounted on the relay flexible printed circuit board near the magnetic head.
The relay flexible printed circuit board includes a signal line, a power source line, and a ground line extending from the magnetic head to the proximal end portion through the head IC,
the main flexible printed circuit board includes a plurality of sets of connection pads, in correspondence with the plurality of head suspension assemblies,
the connection pads of each set includes first, second and third connection pads respectively connected with the signal line, power source line and ground line of the relay flexible printed circuit board, and
the main flexible printed circuit board includes a connection line which connects the plurality of third pads with each other, a ground line extending from one of the third connection pads to the proximal end portion, and a plurality of signal lines extending respectively from the first and second connection pads to the proximal end portion.
With the magnetic disk apparatus having the structure described above, the number of conductive lines in the main flexible printed circuit board can be reduced so that the entire width can be reduced. In this manner, the main flexible printed circuit board can be smoothly deformed, following the operation of the carriage assembly, and the resistance applied to the carriage assembly can be reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.